1. Field of the Invention
The present invention relates to brightness sensors, in particular also brightness sensors for detecting the ambient brightness for regulating electroluminescent elements.
2. Description of the Related Art
Brightness, i.e., incident radiation in the spectra range of visible light, is typically measured using photoelectric sensors. These include photoresistors, photodiodes, photoelements, vacuum photocells, or gas-filled photocells.
If the brightness is measured integrally over a larger area, the typical photoelectric sensors frequently reach limits. These are due to the small dimensions of the areas which absorb light of cited sensors.
The integral light incidence on a larger area is of interest as a measured variable, for example, if the “ambient brightness” or “room brightness” is to be determined, i.e., the illumination of a room as a whole. In contrast, if only the light incidence on a small area is detected here, the measurement result may represent the actual light conditions completely inadequately under certain circumstances. This may be illustrated using the example of a darkened room, in which light is only incident through the door gap. If a small-area brightness sensor happens to lie in the light cone of the door gap, the measurement result would incorrectly indicate a significantly greater ambient brightness than actually exists in the room, viewed integrally.
To measure the integral light incidence on a larger area and/or the mean brightness of the light incident on the area, a remedy if typical brightness sensors are used is employing multiple sensors which are distributed situated over the area, or a movable configuration of one sensor. Both measures are more complex and thus more expensive the higher the area component whose light incidence is actually to be detected. In addition, the light incidence is not actually integrally detected, but rather solely at individual partial areas and then calculated up to the entire area by extrapolation. An extrapolation error accordingly results.